Retina Function – The eye is the most important sense that humans have because it is the sense of sight. You need to know that about 80% of the information humans receive is visual. This is what causes the eye to be one of the senses that work the most among the five senses. All parts of the eye have their respective functions including the retina.
We need to understand the function of the retina in the eye, so we can avoid and understand how to treat diseases that occur in the retina. In this article, we will discuss further about the complete explanation of the retina. So, read this article to the end, Sinaumed’s.
Before knowing about the function of the retina, we need to know what the retina is. The retina is the thin layer of light-sensitive cells in the eye. This thin layer is located behind the eye and plays a role in capturing light. If this layer is disturbed, it can greatly affect your vision system.
Physical structure, in the center there is an optical disc or what is known as a blind spot. This is due to the presence of photoreceptors in the area.
The retina has a very important function for human vision. Inside the retina, there are cells namely rod cells (bacillus) and cone cells (conus). These cells function to trigger nerve impulses through the optics to the brain to form vision. Then the retina will send the signal to the brain through the optic nerve.
Physical structure, in the center there is an optical disc or what is known as a blind spot. This is due to the presence of photoreceptors in the area. If the shadow of an object falls into the blind spot, then the light is not received by the two cells. So humans can’t see it.
Primarily, the function of the retina is to capture light stimuli and organize them into visual information which is then sent to the brain via the optic nerve.
Because the retina has a vital role in vision, the most severe damage can cause permanent blindness. Retinal function can be disrupted, among other things, due to the detachment of the position of the retina in the eye. This condition is known as retinal detachment . When the brain cannot receive information from the retina which eventually leads to blindness.
The retinal area reaches 1100 mm2. The central part of the posterior retina is called the macula lutea. It has a diameter of about 5.5 mm. The color is yellowish due to the presence of luteal pigment (xanthophyll). This macula is responsible for central vision. It had the best visual acuity with the highest spatial resolution.
The center of the macula is called the fovea. It is the thinnest part of the retina and consists only of cone cells (no rods).
Layer of the Retina of the Eye
The retina consists of 10 layers as follows:
- Retinal pigment epithelium or retinal pigment epithelium (RPE). It is the outermost layer of the retina that is in contact with the choroid layer.
- Inner segment or inner segment (IS) and outer segment or outer segment (OS)
- External limiting membrane (ELM).
- The outer nuclear layer of photoreceptor cells or the outer nuclear layer (ONL).
- The outer plexiform layer (OPL).
- The inner nuclear layer or inner nuclear layer (INL).
- The inner plexiform layer (IPL).
- The ganglion cell layer or ganglion cell layer (GCL).
- Nerve fiber layer or nerve fiber layer (NFL).
- Internal limiting membrane or inner limiting membrane (ILM).
How the Retina Works
1. Incoming Light
First, the incoming light will be captured by the eye through the cornea. Next, the cornea will focus the incoming light so that it can enter through the pupil. The dilation of the pupils will be regulated by the iris muscles to determine how much light enters. Then, the light will pass through the eyepiece. The eye lens and cornea work together to focus light on the retina of the eye.
2. Processing Signals
In the retina, photoreceptor cells will receive incoming light, then the signal that is formed will be processed on another neuroretin. Not only detects light, the retina has a function to describe something that has been seen by the eye. This is because the retina has two light receptors, namely rod cells (bacillus) and cone cells (conus).
3. Representing Light
There are 125 million rods and cones in the retina that function as photoreceptors in the eye. When compared, rod cells are indeed more numerous than cone cells, around 18 : 1. Rod cells can function when you see in low light and represent black and white images without the help of a lot of light. When light is available the cones provide the ability to see colors and objects in greater detail. With cone cells, you can even read this text because these cells work to help you see things at high resolution.
For eyes that experience minus or plus, the image captured by the cornea will not fall exactly on the retina. This condition causes what originally functioned as the retina to capture images of objects to appear blurry or even unclear or blurry.
The information received by the rods and cones is then transmitted to nearly one million ganglion cells in the retina. Ganglion cells have the function of interpreting messages from the rods and cones and then sending information to the brain via the optic nerve.
Types of Retinal Diseases
As an important part of our eyesight, we should protect the retina of our eyes from the threat of disease that can infect and eliminate the function of the retina itself. Retinal disease can cause our eyesight to be disturbed, vision to be blurred, vision to be streaked, to the worst is loss of vision. Here are some types of retinal disease that you can know:
1. Retinal detachment
Retinal detachment is a condition where the sensory retinal layer separates or separates from the retinal pigment epithelium (RPE). Detachment of the sensory retinal layer from the RPE causes a shift in the focus of the light so that the sharpness of vision decreases.
Retinal detachment can be said to be an emergency condition that can threaten vision. It can even cause permanent blindness in the most severe cases. Early detection and prompt and appropriate treatment can prevent the threat of this disease.
Several factors that can cause retinal detachment are age, trauma, history of myopia, history of diabetes, and some history of immunological disorders.
2. Diabetic Retinopathy
Diabetic Retinopathy is a retinal microvascular disease due to chronic hyperglycemia in patients with diabetes mellitus (DM).
Diabetes mellitus causes blood vessels throughout the body, including those in the eyes, to become fragile, making them prone to leaks. If these blood vessels leak, complications occur in the eye, especially the vitreous and retinal layers.
Diabetic retinopathy is one of the main causes of visual impairment worldwide in patients aged 20-64 years. The risk factors are age, type, diabetes mellitus, clotting factor disorders, and kidney disease.
3. Hypertensive Retinopathy
Hypertensive retinopathy is a retinal microvascular disease caused by systemic hypertension. The risk of this disease increases the longer you suffer from high blood pressure.
This disease is usually found in patients aged 40 years and over. But it can also occur at younger ages who have high blood pressure above 140 mmHg and diastolic above 90 mmHg.
Retinoblastoma is a malignancy originating from primitive retinal cells, usually occurring in children under 4-5 years of age. This disease is caused by malignant transformation of primitive retinal cells, before the final stage of differentiation.
5. Retinopathy of Prematurity
Retinopathy of prematurity is a retinal vascular disorder in neonates who are born prematurely. This retinal disorder occurs in babies born less than 30 weeks, with a body that is less than 1500 grams. The risk factors for retinopathy are long-term oxygen consumption (more than 7 days) and when the baby is born, the condition does not immediately cry.
6. Retinitis Pigmentosa
Retinitis pigmentosa is a functional disorder of the photoreceptors in the retina, causing the patient to experience impaired vision. Retinitis is an inherited genetic disease.
Retinoblastoma can also be said to be eye cancer. This disease is very serious, starting from the retina triggered by genetic changes in nerve cells. These nerve cells continue to develop into tumors, while normal nerve cells are even covered.
Retinoblastoma usually affects children. But adults can also get this disease. Symptoms include swollen, red eyes and a white dot visible in the middle of the eyeball when exposed to light. Retinoblastoma is a very rare eye disease.
8. Macular Degeneration
Macular degeneration is a disease that is influenced by age. The cause of this disease due to damage to the macula. Generally this disease attacks people aged 50 years.
When the macula is damaged, the function of the retina cannot be optimal. Macular degeneration is divided into two types, namely wet and dry. Dry degeneration is more common, but wet degeneration is more dangerous because of leaky blood vessels in the eye.
9. Central serous retinopathy
Central Serous Retinopathy is a disease that occurs when fluid builds up under the center of the retina and causes vision problems. The disease is more common in men ages 30 to 50 than women, and stress appears to be a major risk factor.
10. Solar Retinopathy
Solar retinopathy is macular damage from staring at the sun and can cause permanent blind spots (scotoma). The risk of this disorder is greatest when viewing a solar eclipse without adequate protection.
11. Epiretinal membrane
The epiretinal membrane is a fine scar tissue or membrane that looks like wrinkled cellophane that sits over the retina. This tissue can tug on the retina and change vision. this can cause objects to appear blurry or crooked.
12. Macular Hole
Macular Holes are small defects in the center of the retina at the back of the eye (macula). This defect can develop from abnormal attraction between the retina and vitreous or it may occur after an eye injury.
13. Retinitis Pigmentosa
Retinitis Pigmentosa is a congenital degenerative disease. This condition slowly affects the retina and causes loss of night vision and side vision. This situation occurs due to the gradual death of photoreceptor cells, especially stem cells caused by genetic disorders.
Retinal Disease Symptoms
Many retinal diseases share some of the same signs and symptoms. Some of the signs you can recognize are:
- Floating black spots/spots (Floaters) or cobwebs,
- Vision is covered in shadows or blurred (straight lines look wavy),
- Narrowed or dark vision,
- Flashes of light in vision (photopsia).
How to Maintain Eye Retina Health
To maintain eye retina health, you need to make sure your nutritional needs are met every day. You need to consume foods that contain vitamin A, vitamin C and vitamin E, lutein, zinc and fatty acids, Omega 3. You can also consume green vegetables, eggs, sea fish and nuts. Here are tips for you to maintain the health of the retina of the eye:
1. Resting the eyes
this is very important for you to do. Especially if you often stare at computer screens, laptops or cellphones and other gadgets. This can cause your eyes to get tired.
You can take your eyes off your computer or gadget screen for 20 seconds every 20 minutes. This aims to maintain the health of the retina of your eyes.
2. Using Sunglasses
Not only used when outside or for fashion accessories, sunglasses also have other benefits such as protecting the retina of the eye. This is because long-term direct exposure to ultraviolet light to the eye can increase the risk of developing cataracts and macular degeneration.
3. Stop Smoking
As we know, smoking is bad for health. One of them is eye health. You can try to stop smoking.
Supporting Examination For Retinal Disease
There are several investigations that are usually done for retinal disease. The following are investigations for retinal disease:
1. Tes Amsler Grid
This examination is carried out to test the clarity of the central vision. This check is carried out using a tool that shows a line drawing. Then the doctor will ask whether the lines seen appear faded, broken, bent, and so on. Then you can see further damage to the retina.
2. Optical Coherence Tomography (OCT)
It can also be said that optical coherence tomography is a technique to capture precise images of the Retina to diagnose epiRetinal membrane, macular holes, and macular swellings. This aims to monitor the extent to which macular degeneration affects vision.
3. Angiografi Fluoresens
This test uses a dye that causes the blood vessels in the retina to show up clearly under a special light. This test aims to identify closed blood vessels, leaky blood vessels, new abnormal blood vessels and changes in the results behind the eye.
4. Eye ultrasound
This exam uses high-frequency sound waves to help see the retina and other structures inside the eye. In addition, ultrasound can also be done to identify certain tissue characteristics that can help diagnose and treat eye tumors.
5. CT and MRI
In some rare cases, this method can be used to help evaluate the presence of an eye injury or tumor which is a risk factor for retinal disease.
Retinal Disease Treatment
There are several treatments that can be done to cure retinal diseases, as follows:
- Abnormal shrinkage of blood vessels
- Freezing (Cryopexy)
- Inject air or gas into the eye
- Scleral Buckling Operation
- Evacuate and replace fluid in the eye
- Inject medication into the eye